Sustainable Transportation Center, Urban Land Use and Transportation Center
In their search for effective ways to encourage physical activity, public health officials have turned their attention to the built environment, focusing in particular on how neighborhood design can support walking and biking. Numerous studies have documented a connection between neighborhood design and active travel (i.e., walking and bicycling for transportation rather than for recreation) among both children and adults. For example, residents walk more for transportation in traditionally designed neighborhoods — those with safe sidewalks and intersections, and a street network that provides direct access to nearby shops and other destinations — than they do in typical U.S. suburban neighborhoods, where homes are separated from destinations by major roads that hinder walking or biking.
While there clearly is a link between neighborhood design and active travel, there are still questions about the nature of the cause-and-effect relationship that exists between them. Do places designed for walking encourage people to walk more, or do people who like to walk prefer to live in places that are designed for walking? The latter, what researchers call “self-selection,” is an important consideration when determining how best to increase opportunities for physical activity. If differences in active travel exist because residents who already are active self-select into neighborhoods that support such travel, then improvements to the walking environment may not encourage residents to walk more. But infrastructure improvements could still lead to increases in active travel by making it possible for more people who prefer walking or biking to live in neighborhoods that support such activities.
Researchers have employed different approaches to determine whether and to what degree self-selection occurs, though many studies focus on travel by all modes rather than just on active travel. As demonstrated by the research presented in this brief, consistent evidence is beginning to emerge that shows both self-selection and the built environment have a role in active travel.
Suggested citation: Handy, Susan L., Xinyu Cao, Patricia L. Mokhtarian. Active Travel: The Role of Self-Selection in Explaining the Effect of Built Environment on Active Travel. Active Living Research (ALR) Research Brief, Fall 2009.